A past innovation for water conservation is proving prone to failure resulting in huge water losses
Billions of litres of water are being wasted every week because of an innovation intended to cut water use.
About 400 million litres (88 million gallons) of water are estimated to leak from UK toilets every day. But much of this can be blamed on dual-flush toilets, designed to save water. One water company says dual-flush toilets are now wasting more water than they save due to a combination of leaky mechanisms and confusing flush buttons. Dual-flush toilets allow the option of a small or large flush - typically four or six litres - to only use the water necessary for urine or faeces. Water-saving organization Waterwise estimates that between 5% and 8% of toilets are leaking and says most of these are dual flush.
"The volume of water loss is getting bigger every day as more people refurbish and retrofit their older toilets and as we build more homes, so we're actually adding a problem."
Andrew Tucker, water efficiency manager at Thames Water, the UK's largest water and sewerage company, is quoted in national press as saying "the problem is getting worse as bathrooms are done up. Because we've got so many toilets that continuously flow all through the day, collectively that water loss is now exceeding the amount of water they should be saving nationally," he said. "The volume of water loss is getting bigger every day as more people refurbish and retrofit their older toilets and as we build more homes, so we're actually adding a problem."
Most dual-flush toilets use a drop valve system, which was allowed onto the UK market back in 2001 due to a change in regulations.
The UK's Bathroom Manufacturers Association (BMA) admits the drop valve system is more prone to leakage than the traditional siphon if not maintained.
The drop valve, which opens for a flush, sits underwater at the bottom of the cistern. Debris - like porcelain, grit or calcium - easily catches in the valve causing leaks which can then run constantly, meaning this is a fundamental design issue and not specific to any particular manufacturer or model. The siphon, on the other hand, works when the flush handle forces a volume of water over a lip down into a tube linked to the pan. Water's only way out is above the water line, making leakage very rare.
"If we're serious about wasting water and we want to stop it, the only way to do that is put a siphon back in,"
Thomas Dudley Ltd, one of the UK's largest plumbing manufacturers, has a testing station that puts any new mechanism through its paces with 200,000 constantly repeated flushes, taking four months. Managing director Jason Parker says: "A siphon will not leak whereas an outlet valve - if we look at the figures we've got - they could leak within a week of installation. It could be two years but they will leak." Siphons are now being made dual flush, so he wants drop valves outlawed despite the fact they are his biggest seller and such a move could harm his business. "If we're serious about wasting water and we want to stop it, the only way to do that is put a siphon back in," he says.
And that is not the only issue
Leaking valves are not the only issue impacting water efficiency, water is also lost by confusion over buttons. Style over substance has made many unclear which button does what. Thames Water says in recent research as many as 50% of customers chose the wrong button - or pushed both.
How do I know if this affects my building?
A leak can be silent but there may be a small ripple at the back of the bowl. Some water companies suggest wiping the back of the bowl dry 30 minutes after a flush and placing a square of toilet paper there overnight - if it is wet or torn in the morning there is a leak. Alternatively drain fluorescein, a fluorescent marker for tracing drainage flows, or even food colouring can be put in the cistern between flushes to see whether it shows up in the toilet pan.
A number of our water conservation measures will help you identify, quantify and remediate this problem, click on the adjacent image to access your free sustainability resource centre.
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